Orbital ATK is still continuing development of their in house designed launch vehicle - Antares rocket; Company is considering July 2016 as most possible date for first launch since disaster in 2014.
Antares failed launch which took place on 28 October 2014 in Wallops Flight Facility did not stopped participation of Orbital ATK in Commercial Resupply Service contract which covered using Cygnus robotic spacecraft combined with Antares rocket. Orbital ATK to keep the schedule of cargo missions was forced to sign contract with United Launch Alliance and use their Atlas V rocket. Surely it was not economically advantageous solution but helped go through tough period without breaking contract. After over year of hard work, Orbital ATK announced in February 2016 that they will fly upgraded Antares with Cygnus on atop in the first half of 2016 - on 31st May. Unfortunately due the delays launch was postponed two times and ultimately it was scheduled for 6th July 2016. Delays are fully understandable because new version of Antares is basing on Russian RD-181 engines instead of post-Soviet NK-33 (renovated and prepared by Aerojet Rocketdyne as AJ26) along with extended Castor-30XL boosters which are stretched Castor-30A used in previous version of Antares. Orbital ATK is targeting for two launches of their rocket in 2016: in July and in November, both with Cygnus cargo spacecraft on atop. According to Orbital ATK President David Thompson (who gave announcement in Paris on 5th May 2016) new Antares will be rolled out in Wallops Flight Facility for preparing static fire test next week. It everything will go as planned, launch scheduled for 6th July 2016 and performed from Mid-Atlantic Regional Spaceport (MARS) at NASA's Wallops Flight Facility on Wallops Island will be probably performed without further delays.
Orbital ATK is still trying to offer Antares for customers in future. Due the fact that Orbital ATK is large company Operating in many market segments, Antares was not built from scratch with engines like Falcon-9 by SpaceX and many technologies used during designing this rocket is used in other products by Orbital ATK. That is why Orbital is not in great rush with Antares and according to David Thompson Company is considering as profitable if three launches of Antares will be performed annually (including CRS missions).
On picture above: Antares in 2013 over Wallops Flight Facility.